Method of constructing a liquid-tight side wall for shipping containers



Aug. 26, 1969 METHOD OF CONSTRUCTING A LIQUID-TIGHT SIDE WALL FOR SHIPPING CONTAINERS Filed Aug. 22. 1966 United States Patent 3,463,059 METHOD OF CONSTRUCTING A LIQUID-TIGHT SIDE WALL FOR SHIPPING CONTAINERS Johnny Vonk, Shertogenbosch, Netherlands, assignor to Inland Steel Company, Chicago, 11]., a corporation of Delaware Filed Aug. 22, 1966, Ser. No. 574,119 Int. Cl. 1331c 13/00 US. Cl. 93-77 4 Claims The present invention relates generally to shipping containers, such as drums, and, more particularly, to lined shipping containers. In its principal aspects the invention is concerned with improved methods and apparatus for forming lined shipping containers, as well as to improved lined shipping containers formed thereby.

Shipping containers of the general type concerned here commonly comprise a cylindrical body having a reinforced inwardly extending circumferential bead and a chime at each end, with the ends being additionally provided with suitable closures. The container wall may be of any suitable material, but the present invention finds particularly advantageous use in connection with containers wherein the body is made of fibre, paper board filaments, or similar porous materials which may be either natural or synthetic. The invention is not, however, limited to use with container side walls formed of such material but, on the contrary, it will also find applicability with containers having side walls formed of steel or other impervious material with certain modifications as described herein.

Containers of this general type are often utilized for the transport of liquids or of materials having a high percentage of liquid content. Since side wall materials such as fibre, paper board and the like are not generally liquidtight, the interior of the container body wall is provided with a liquid-tight lining of flexible sheet material such as polyethylene. Moreover, when dealing with liquid-tight steel drums or the like, similar internal linings are often provided, particularly where the container is to be used to transport aggressive commodities. With such a lining, difficulties are often encountered in achieving a smooth fit and tight adherence to the container inner wall, particularly in the vicinity of the chime, or in the vicinity of the inwardly extending bead or where a similar inner convolution is present. It is highly desirable to form the chime and other convolutions prior to the installation of the tubular internal lining so as to avoid damage to the lining resulting from the forming process, but this has heretofore presented difiicul-ties. In drawing the lining tightly against the internal Walls of the container, the liner is likely to remain stretched between the inwardly extending beads, or between one bead and the opposite chime end of the container, rather than lying smoothly against the inner wall surface. Such a condition is not only wasteful of space because of the trapped volume between the liner and the internal wall, but the liner is substantially unsupported in this position and prone to punctures or other damage.

It is, therefore, a general aim of the present invention to overcome the foregoing ditficulties and to provide an improved shipping container side wall and method of manufacture thereof characterized in that the side wall is provided with a liquid-tight internal plastic liner which smoothly conforms and adheres to the inner surface of the container.

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In another of its important aspects, it is an object of the invention to provide improved methods and apparatus for forming an internally lined container side wall of the character described characterized by exceptional versatility in that such methods and apparatus find equal applicability in lining a Wide variety of different types of side walls whether the latter are made of pervious material such as fibre or impervious materials such as steel.

Other objects and advantages of the invention will become apparent as the following description proceeds, taken in conjunction with the accompanying drawing, in which:

FIG. 1 is a side elevational view, in half-section, here depicting an exemplary apparatus for forming lined shipping containers embodying the features of the invention in accordance with the novel method of the invention, the container and its lining here being shown in an initial stage of the forming process;

FIG. 2 is an enlarged partial section of a corner of the shipping container side wall and apparatus of FIGURE 1 here illustrating the liner in broken lines prior to the forming operation and in solid lines after such operation; and

FIG. 3 is a slightly reduced partial section similar to FIG. 2, but here illustrating a slightly modified side wall construction also embodying the features of the present invention.

While the invention is susceptible of various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawing and will herein be described in detail. It should be understood, however, that it is not intended to limit the invention to the particular forms disclosed, but, on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as expressed in the appended claims.

Turning now to the drawings, there is shown in FIG- URE 1 an exemplary apparatus suitable for carrying out the method of the present invention. The illustrative apparatus comprises a heavy air-tight cylindrical vacuum vessel 10 closed at one end by a welded end plate 11, such that the resulting vessel defines a chamber of suflicient diameter and depth to accommodate a shipping container side wall 12. A lid 13 having a vent 15 is provided for the vessel 10 and is secured about its circumference by a plurality of fasteners 16. The container side wall 12 is not fitted with end closures at this stage of its construction, and its interior is thereby vented to the atmosphere through the vent opening 15.

For the purpose of defining a sealed annular space between the side wall 12 and the vessel 10 a flat circumferential gasket 17 is provided at the bottom of the vessel 10 of sufiicient diameter and width to underlie and seal the lower periphery of the side wall 12. A corresponding gasket 18 is provided at the top of the vessel 10 where it is clamped in sealing relationship between the vessel and the lid 13 as well as sealing the upper periphery of .the side wall 12. The dimensions of the vessel 10 are chosen such that when a container side wall 12 is lowered into place and the lid 13 is clamped down, the gaskets 17, 18 are deformably urged against the ends of the side wall 12 to form a tight seal. The result is that an annular area surrounding the outside of the side Wall 12 is rendered airtight, while the opening 15 vents the inside of the container to the atmosphere.

For providing reinforcement and stiffness at the vulnerable chime region near the ends of the container, a

circumferential bead or flange 25 is generally formed at each end of the container side wall 12 prior to being placed into the vacuum vessel 10. Also surrounding the chime area of the container side wall 12, although not necessarily, is a rolled reinforcing ring 26 which is formed by crimping, wheeling, turning, or any other suitable method so as to conform with the shape of the beaded side wall extremity. As a practical matter, the flange or bead 25 in the side wall is normally formed at the same time as the complemental bead in the reinforcing ring 26 in a manner well known to those skilled in the art.

In carrying out the invention, a tubular section of liquid-tight plastic sheet material 28 is positioned within the previously formed side wall 12. To temporarily hold it in place, its ends 29 are drawn back over the ends of the side wall 12 as shown in FIG. 2. In this condition (represented by dotted lines in FIG. 2), the liquid liner does not conform to the inner convolutions of the container side wall 12, but is instead drawn loosely between the upper head 25 and the corresponding lower bead 25 at the other end of the side wall. The liner 28 is also generally somewhat resilient, and resists being forced into smooth conformity with the inner surface of the side wall 12.

It should be noted that the inner liner 28 may be made of various materials and with differing construction. Any suitable sheet material may be used, such as polyethylene, polyvinyl chloride, or other similar liquidtight material. It is formed preferably as a seamless extruded tube, or in the alternative fabricated into tube form from sheet material with a heat-sealed or taped seam where the ends of the sheet abut or overlap.

In carrying out the invention, care is taken that the ends 29 of the inner liner 28 which are turned over the ends of the side wall 12 are located in sealing relationship to the gaskets 1'7, 18 when the side wall is placed in the vacuum vessel 10. After the side wall 12 and its liner 23 are properly located, the lid 13 is clamped securely into place and a heating element 30 is lowered into a central position within the container wall 12 as shown in FIGURE 1. The process is preferably initiated by energizing the heating element 30 to controllably heat the liquid-tight liner 28 to a degree whereby the liner losses its resilience and becomes somewhat plastic, and additionally acquires a degree of adhesivenes.

Pursuant to the invention, the liner 28 is drawn into adherent contact with the side wall 12 by creating a pressure differential between the region within the side wall adjacent the heating element 30 and the annular region between the liner and the side wall.

For achieving the required pressure differential, the annular region exterior to the side wall 12 is evacuated by a vacuum pump 31 through a vacuum fitting 32. Because of the air-permeable porous nature of the side wall 12, the air within the annular space is also evacuated, thereby causing the pressure within the region adjacent the heating element 20 (which is vented to the atmosphere by the vent 15) to force the now-softened liner 28 into conformity with the inner surface of the container side wall 12. This combination of heat and pressure causes the liner 28 to smoothly conform to and be adhesively secured to the side wall 12, at which point the heating element 30 is de-energized or removed. The side wall assembly, with the inner liner now firmly bonded to the side wall 12, is allowed to cool. The vacuum pump 31 may then be turned off and the vacuum within the annular space within the vacuum chamber released. The lid 13 is removed, the bonded side wall and liner assembly 12 taken out, and the process may then be repeated for another side wall assembly and inner liner 28.

In an alternative embodiment of the present invention, as illustrated in FIG. 3, a container side wall 33 made of steel or other impervious material may also be utilized, but with the additional provision of a plurality of perforations or vent holes 34- provided around its periphery.

As in the case of fibre side walls, a circumferential reinforcing ring 36 is provided for stiffening the vulnerable chime area. In this embodiment it has been found to be possible to extend the lower edge of the reinforcing ring 36 below the level of the vent holes 34. The entrapped air within the space between the inner liner 28 and the side wall 33 may still escape, however, because the reinforcing ring 36 is not rolled against the side wall 33 so tightly as to completely close off the vent holes 34. The vent holes 34 are therefore preferably positioned so as to just be covered by the reinforcing ring 36 beneath its lower edge. They are protected by the ring 36 to prevent moisture or dirt from penetrating into the openings, while not being sealed to an extent that the escape of entrapped air is prevented.

It should be noted that it is also possible to carry out the invention by initiating operation of the vacuum pump 31 prior to or simultaneous with energization of the heating element 30. In either event, the liquid-tight inner liner 28 is softened and made adhesive as it is drawn toward the side wall 12, and is caused to adhere when contact is achieved through the exhaustion of the entrapped air. When this has been accomplished the heating is terminated, the vacuum released, and the completed side wall assembly removed as before.

The result is a container side wall 12 having, in the preferred embodiment, a continuously adhering liquidtight lining 28 free of Wrinkles and other imperfections. The lining is also free of any damage which might have otherwise been suffered from forming the chime or applying the reinforcing band 22 subsequent to the addition of the liner 28, as is often encountered when such operations are performed on container materials having a previously applied plastic coating.

A complete container is then formed from the completed side wall assembly 12 by securing suitable top and bottom closures (not shown). For this purpose, the internal convolutions or beads 25 may be used as supports against which the closures may be secured in known fashion.

I claim in my invention:

1. Apparatus for forming a liquid-tight shipping container side wall, said apparatus comprising the combination of an annular vacuum vessel adapted to receive a tubular air-permeable side wall that is open at both ends and a preformed liquid-tight tubular liner of air-impermeable flexible sheet material disposed within said side wall and extending beyond the ends of said side wall, sealing gasket means at both ends of said vacuum vessel for forming a seal between said vacuum vessel and said side wall, said sealing gasket means pressing the end portions of said liner against the corresponding ends of said side wall when said end portions of said liner are turned over the corresponding ends of said side Wall, said vacuum vessel and said sealing gasket means forming a substantially uniform annular vacuum chamber between the inner surface of said vacuum vessel and the outer surface of said side wall and extending along substantially the entire length thereof, a heating element disposed within the interior of said side Wall to render said tubular liner plastically deformable, and means for drawing a vacuum within said annular vacuum chamber to draw said liner into adherent contact with substantially the entire inner surface of said side wall.

2. Apparatus according to claim 1 in which said side wall includes an inturned annular bead and a chime formed at one inner wall end of said side wall prior to positioning said liquid-tight liner within said side wall.

3. Apparatus according to claim 1 in which the airpermeable side wall is of fibrous material.

4. Apparatus according to claim 1 in which said side wall is of impervious material having a plurality of perforated vents.

(References on following page) References Cited UNITED STATES PATENTS Howard 93-'77 Reid 93-77 Walton 22914 5 Wilcox 156160 Thompson 93-3601 McGee 93-36.01

McArdle 93--36.01 Gardner 9336.01 X 10 Winstead 9336.01 X

Carpenter 9394 Taggart 93--36.01 McGee 93'36.01 X

WAYNE A. MORSE, 111., Primary Examiner US. Cl. X.R. 

1. APPARATUS FOR FORMING A LIQUID-TIGHT SHIPPING CONTAINER SIDE WALL, SAID APPARATUS COMPRISING THE COMBINATION OF AN ANNULAR VACUUM VESSEL ADAPTED TO RECEIVE A TUBULAR AIR-PERMEABLE SIDE WALL THAT IS OPEN AT BOTH ENDS AND A PREFORMED LIQUID-TIGHT TUBULAR LINER OF AIR-IMPERMEABLE FLEXIBLE SHEET MATERIAL DISPOSED WITHIN SAID SIDE WALL AND EXTENDING BEYOND THE ENDS OF SAID SIDE WALL, SEALING GASKET MEANS AT BOTH ENDS OF SAID VACUUM VESSEL FOR FORMING A SEAL BETWEEN SAID VACUUM VESSEL AND SAID SIDE WALL, SAID SEALING GASKET MEANS PRESSING THE END PORTIONS OF SAID LINER AGAINST THE CORRESPONDING ENDS OF SAID SIDE WALL WHEN SAID END PORTIONS OF SAID LINER ARE TURNED OVER THE CORRESPONDING ENDS OF SAID SIDE WALL, SAID 